Transmission auxiliary unit timed shift inhibitor

ABSTRACT

An embodiment provides a shift inhibitor apparatus. At least a portion of the range actuating assembly is moveable between a range first ratio and a range second ratio. The portion of the range actuating assembly is moveable, at least in part, in response to a fluid pressure. The range chamber is selectively in fluid communication with a vent. The shift inhibitor includes a main section neutral interlock having an interlock chamber. At least a portion of the main section neutral interlock is moveable between a first condition and a second condition. The interlock chamber is selectively in fluid communication with the vent. The range chamber can be exhausted such that the range section is selectively switched from the first ratio to the second ratio. The interlock chamber can be exhausted such that the main section neutral interlock is selectively switched from the first condition to the second condition.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Application60/630,174, filed on Nov. 22, 2004, the contents of which are herebyincorporated by reference herein in their entirety.

TECHNICAL FIELD

The technical field is generally control systems for shifting theauxiliary sections of compound transmissions, and particularly,pneumatic control and interlock systems for a range type compoundtransmission.

BACKGROUND

Compound transmissions of the range or combined range/splitter type arewell known in the prior art. Such transmissions typically comprise amultiple speed main transmission section connected in series with arange type auxiliary section wherein the range step is greater than thetotal ratio coverage of the main transmission section.

In such transmissions, the main section is typically shifted by means ofa shift housing assembly controlled by a manually operated shift leveror the like. In contrast, the auxiliary range section is shifted bymeans of a button or switch. In the prior art, a switch operated by themain section shift mechanism controls a remote slave valve/actuatormechanism. The valve/actuator mechanism controls operation of a rangeselection actuator. The range selection cylinder includes afluid-actuated piston that divides an actuator cylinder into a low-rangeand a high-range chamber. The piston is made to move in response toselective pressurization of one chamber while simultaneously exhaustinga second chamber. Since the range section often utilizes synchronizedjaw clutches, a range shift is preferably initiated and completed whilethe main transmission section is in neutral, to provide acceptable shiftquality and to prevent undue wear and/or damage to the synchronized jawclutches.

Prior art compound range type transmissions usually include a controlsystem, which is typically a pneumatic control system having interlockdevices, that allows a range shift to be preselected using a selectorbutton or switch at a master control valve. To prevent damage to the jawclutches, the control system prevents shift initiation until the maintransmission section is shifted to, or at least towards, the neutralcondition. One method for preventing shift initiation utilizesmechanical type interlock devices on the range section actuatormechanical linkage that physically prevent movement of the range sectionshift fork until the main section is shifted into neutral. A second,more common method of preventing shift initiation utilizes logic-basedinterlock devices of the type wherein the valve supplying pressurizedfluid to the range section cylinder is either disabled or not providedwith pressurized fluid until a shift to main section neutral is sensed,or is only activated and provided with pressurized fluid while the mainsection is shifted to and remains in neutral. Examples of suchtransmissions and the control systems therefor may be seen by referenceto U.S. Pat. Nos. 2,654,268; 3,138,965, 4,060,005 and 4,974,474.

Prior art systems are particularly concerned with protecting the rangesynchronizer during range upshifts, or upshifts to the high range. Ithas been discovered that for certain systems, successful completion of ahigh range shift is more likely to be achieved in a timely fashionrelative to the shifting of the main section. In such transmissions, itis highly desirable to provide a mechanism for protecting the low rangesynchronizer.

SUMMARY

An embodiment provides a shift inhibitor apparatus for a multiple speedtransmission main section. The transmission includes an input shaft andan output shaft. The transmission main section has a plurality ofselectively engageable ratios. The transmission also has a range sectionshiftable between a range high ratio and a range low ratio. The shiftinhibitor includes a range actuating assembly having a range chamber. Atleast a portion of the range actuating assembly is moveable between arange first ratio and a range second ratio. The portion of the rangeactuating assembly is moveable, at least in part, in response to a fluidpressure. The range chamber is selectively in fluid communication with avent. The shift inhibitor includes a main section neutral interlockhaving an interlock chamber. At least a portion of the main sectionneutral interlock is moveable between a first condition and a secondcondition. The interlock chamber is selectively in fluid communicationwith the vent. The range chamber can be exhausted such that the rangesection is selectively switched from the first ratio to the secondratio. The interlock chamber can be exhausted such that the main sectionneutral interlock is selectively switched from the first condition tothe second condition.

In an embodiment, a shift apparatus for encouraging the completion of arange shift in a range section of multispeed transmission prior to thecompletion of a main shift in a main section of the multispeedtransmission is provided. The transmission includes an input shaft andan output shaft. The transmission main section has a plurality ofselectively engageable ratios. The transmission has a range sectionshiftable between a first ratio and a second ratio. The apparatusincludes a range actuating assembly having a range chamber. At least aportion of the range actuating assembly is moveable between a firstposition and a second position to shift the range section from the firstratio to the second ratio. The portion of the range actuating assemblyis moveable, at least in part, in response to a fluid pressure. Theapparatus includes a vent in selective fluid communication with therange chamber, and a first transmitter for introducing a first fluidforce within the range actuating assembly. The apparatus also includes asecond transmitter for introducing a second fluid force within the rangeactuating assembly. A first fluid pressure is selectively supplied tothe range actuating assembly when the shift member is engaged in apreselected gear.

An embodiment provides a method of encouraging the completion of a rangeshift in a range section of multispeed transmission prior to thecompletion of a main shift in a main section of the multispeedtransmission. The multispeed transmission includes an input shaft, anoutput shaft, a range section shiftable between a first ratio and asecond ratio. The main section has a plurality of selectable gearratios. The method includes the step of shifting the main section from afirst predetermined gear to a second predetermined gear. The step ofshifting the main section includes the steps of initiating a shiftbetween gears of the main section and completing the shift between gearsof the main section. The method includes the step of detecting aposition of a shift member. The step of detecting is performed after thestep of initiating the shift between gears of the main section andbefore the step of completing the shift between gears of the mainsection. The method also includes the step of shifting the range sectionfrom the first ratio to the second ratio. The step of shifting the rangesection includes the steps of initiating a shift between gears of therange section and completing the shift between gears of the rangesection. The step of shifting the range section is performed, at leastin part, by a fluid actuated device. The method further includes thestep of ensuring the step of completing the shift between gears of therange section is performed before the step of completing the shiftbetween gears of the main section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration, not to scale, of a compoundtransmission having a range type auxiliary section and utilizing thepneumatic control system.

FIG. 2 is a schematic illustration of the exterior components of theshift mechanism of the transmission of FIG. 1.

FIG. 3 is a schematic illustration of the shift housing element of themain section and the range actuator assembly of the transmission of FIG.1.

FIG. 4 is a perspective view of the shift housing assembly together withthe mainshaft assembly of the transmission of FIG. 1 from theback/left/top directions.

FIG. 5 is a perspective view of the shift housing assembly together withthe selector mechanism of the transmission of FIG. 1 from theback/left/bottom directions.

FIG. 6 is a perspective view of the shaft assemblies of the main sectionof the transmission of FIG. 1.

FIG. 7 is a schematic illustration of the shift gate arrangement of thetransmission of FIG. 1 taken along the direction of arrow 7 in FIG. 4.

FIG. 8 is a schematic illustration of the shift pattern of thetransmission of FIG. 1.

FIG. 9 is a perspective exploded view of the selector mechanism of FIG.5 in the general direction of the view of FIG. 4.

FIG. 10 is an enlarged broken out partial view of the portion of FIG. 9found in circle 10.

FIG. 11 is a section view of the selector mechanism taken in thedirection of line 11-11 in FIG. 9, and illustrating a dual pressureswitch.

FIGS. 12A, 12B, 12C, and 12D are partial section views of the selectormechanism in the direction of line 12-12 in FIG. 11, illustratingexemplary relative component locations during operation.

FIG. 13 is a partial section view of the selector mechanism, similar toFIGS. 12A, 12B, 12C, and 12D.

FIG. 14 is a partial section view of an embodiment of the range sectionof an exemplary transmission.

FIG. 15 is an exemplary schematic diagram of the air supply routing fora first embodiment.

FIG. 16 is an exemplary schematic diagram of the air supply routing fora second embodiment.

FIG. 17 is an exemplary schematic diagram of the air supply routing forthe second embodiment and some relevant components in section.

FIG. 18 is an exemplary schematic diagram of the air supply routing fora third embodiment and some relevant components in section.

FIG. 19 is a schematic illustration of a shift pattern.

DETAILED DESCRIPTION

Referring to FIGS. 1, 2 and 3, a range type compound transmission 10 isillustrated. Compound transmission 10 comprises a multiple speed maintransmission section 12 connected in series with a range type auxiliarysection 14. Transmission 10 is housed within a housing (not shown) andincludes an input shaft 16 driven by a prime mover such as diesel engineE through a selectively disengaged, normally engaged friction masterclutch C having an input or driving portion 18 drivingly connected tothe engine crankshaft 20 and a driven portion 22 rotatably fixed to thetransmission input shaft 16.

In main section 12, the input shaft 16 carries an input gear 24 forsimultaneously driving a pair of countershaft assemblies 26 atsubstantially identical rotational speeds. The two countershaftassemblies 26, which may be substantially identical, are illustrated ondiametrically opposite sides of the mainshaft 28 which is generallycoaxially aligned with the input shaft 16. Each of the countershaftassemblies 26 comprises a countershaft 30 supported by bearings 32 and34 in the housing. Each of the countershaft assemblies 26 is providedwith a grouping of countershaft gears 38, 40, 42, 44, 46 and 48, fixedfor rotation therewith. A plurality of mainshaft gears 50, 52, 54, 56and 58 surround the mainshaft 28 and are selectively clutchable, one ata time, to the mainshaft 28 for rotation therewith by sliding clutchcollars 60, 62 and 64, as is well known in the prior art. Clutch collar60 may also be utilized to clutch input gear 24 to mainshaft 28 toprovide a direct drive relationship between input shaft 16 and mainshaft28.

Mainshaft gear 58 is the reverse gear and is in continuous meshingengagement with countershaft gears 48 by means of conventionalintermediate idler gears (not shown). It should also be noted that whilemain section 12 does provide five selectable forward speed ratios, thelowest forward speed ratio, namely that provided by drivingly connectingmainshaft drive gear 56 to mainshaft 28, is often of such a high gearreduction it has to be considered a low or “creeper” gear which isutilized only for starting of a vehicle under severe conditions and, isnot usually utilized in the high transmission range. Accordingly, whilemain section 12 does provide five forward speeds, it is usually referredto as a “four plus one” main section as only four of the forward speedsare compounded by the auxiliary range section 14 utilized therewith.

With continual reference to FIG. 1, auxiliary transmission range section14 includes two substantially identical auxiliary countershaftassemblies 74 each comprising an auxiliary countershaft 76 supported bybearings 78 and 80 in housing H and carrying two auxiliary sectioncountershaft gears 82 and 84 for rotation therewith. Auxiliarycountershaft gears 82 are constantly meshed with and support a rangeinput/main section output gear 86 that is fixed to mainshaft 28.Auxiliary section countershaft gears 84 are constantly meshed with anauxiliary section output gear 88 that surrounds transmission outputshaft 90.

With specific reference to FIGS. 1 and 3, the auxiliary transmissionrange section 14 further includes a synchronized two-position auxiliarysection jaw clutch assembly 92. The jaw clutch assembly 92 is axiallypositioned by means of a range shift fork 94 (also illustrated in FIG.14). The jaw clutch assembly 92 is rotatably fixed to output shaft 90for rotation therewith. A range section shifting actuator assembly 96 isprovided for clutching either gear 88 to output shaft 90 for low rangeoperation, or gear 86 and mainshaft 28 to output shaft 90 for direct orhigh range operation of the compound transmission 10, as discussed ingreater detail below.

With reference to FIGS. 3-7, the shifting of gears in the main section12 will be described in greater detail. Typically, clutch collars 60, 62and 64 are axially positioned by means of shift forks 100, 102 and 104,respectively. Clutch collars 60, 62 and 64 may be of the well knownsynchronized or nonsynchronized double acting jaw clutch type. In theexemplary embodiment, clutch collars 60 and 62 are synchronized, andclutch collar 64 is nonsynchronized.

Clutch collars 60, 62, and 64 are three-position clutches in that theymay be positioned, as illustrated in FIG. 1, in the centered nonengagedposition, in a fore engaged position or in an aft engaged position bymeans of shift forks 100, 102, and 104 respectively. In the illustratedembodiment, and as best seen in FIGS. 4 and 5, shift forks 100, 102, and104 are integrated into a shift housing assembly 110. The shift forks100, 102, and 104 extend from the shift housing assembly 110 and arecontrolled by a selector mechanism 112 (as best seen in FIGS. 2, 5, and9) positioned over housing assembly 110, as described below. Selectormechanism 112 is in turn controlled by an operator manipulatedtransmission input device, or shift lever, 114 (FIG. 2). Shift lever 114is connected to selector mechanism 112 through an intermediate shiftlinkage 116, and may be disposed some distance from selector mechanism112. In the embodiment illustrated, only one of the clutch collars 60,62 and 64 is engageable at a given time and a main section interlockmeans (not shown) may be provided to lock the other clutches in theneutral condition. As discussed in greater detail below, the user needonly manually manipulate a single shift lever 114 in order to shift boththe main section 12 and the range section 14.

The main section 12 is controlled by axial movement of, in theillustrated embodiment, three shift rails 120, 122 and 124 containedwithin the shift housing assembly 110 and controlled by operation of theshift lever 114 via the intermediately disposed selector mechanism 112,as shown in FIGS. 2-8. Alternative mechanisms to the three rail shiftarrangement may be employed, with such mechanism having more shiftrails, or just a single shift rail such as the one shown in U.S. Pat.No. 4,621,537.

With specific reference to FIG. 7, the shift forks 100, 102, 104 havecorresponding shift gates 130, 132, 134 for the Lo-R, 1-2 and 3-4 gearranges respectively (FIG. 8). A 5-6 shift gate 136 and a 7-8 shift gate138 provide high range gear ratios, as discussed below. Shift fork 100,with integral shift gates 134 and 138, is affixed to shift rail 124.Shift fork 102, with integral shift gates 132 and 136, is affixed toshift rail 122. Shift fork 104, with integral shift gate 130, is fixedto shift rail 120. As illustrated in FIG. 7, main section 12 is in aneutral condition, where clutch collars 60, 62, 64 are not engaged.

With reference to FIG. 8, a shift pattern 142 for the shift lever 114 ofthe transmission 10 is illustrated. Shift pattern 142 includes a 3-4throw position 144 and a 5-6 throw position 146. Referring to both FIGS.7 and 8, shift gate 130 corresponds to a Lo-R shift throw. That is, whenthe shift lever 114 is generally in the Lo-R shift throw position, theshift lever 114 may be moved in the fore direction to place the shiftlever 114 in the R shift position. When shift lever 114 is in the Rshift position, the main section 12 of the transmission 10 is in‘reverse’ with the mainshaft gear 58 ‘engaged’ with the clutch collar64. Similarly, when the shift lever 114 is generally in the Lo-R shiftthrow position, the shift lever 114 may be moved in the aft direction toplace the shift lever 114 in the Lo shift position. When shift lever 114is in the Lo shift position, the main section 12 of the transmission 10is in ‘low gear’ with the mainshaft gear 56 engaged with the clutchcollar 64. Accordingly, when the shift lever 114 is generally in theLo-R shift throw position, the transmission 10 is in the Lo-R shiftrange, and shift lever 114 may be manipulated to translate the shiftgate 130. Shift lever 114 operates similarly when in the 1-2, 3-4, 5-6,and 7-8 throw positions. Shift pattern 142 also includes multipleneutral positions, such as N1 and N2. As described below, the rangesection 14 will be in engaged in a range low ratio when shift lever 114is in neutral position N1, and the range section 14 will be in engagedin a range high ratio when shift lever 114 is in neutral position N2.

As best illustrated in FIG. 9, selector mechanism 112 also includes ashift finger 140 of selector mechanism 112 is selectively disposed inone of the shift gates 130, 132, 134, 136, 138. Movement of shift finger140 displaces a selected one of the forks and thereby engages a targetgear. Movement of shift lever 114 controls the position of shift finger140.

In the exemplary embodiments, selector mechanism 112 may include aposition switch 150. While an embodiment of the position switch 150 isillustrated in FIG. 9, a possible location of the position switch 150within the shift pattern of the transmission 10. Shifting of theauxiliary or range section 14 is controlled by operation of a positionswitch 150 integrated into selector mechanism 112 as is well known inthe prior art. The selector mechanism 112 and the shift housing assemblyof the preferred embodiment together provide a “double H” type shiftpattern as illustrated in FIG. 8. Position switch 150 is a fluid typeswitch, specifically a pneumatic switch. It is to be appreciated thatposition switch 150 may alternatively be characterized as a valve.Position switch 150 has a plunger 152 which displaces a valve within avalve body (not shown). Position switch 150 communicates pressurizedtruck service air to the range section shifting actuator assembly 96 toeffect shifts between the low and high ranges. Such pneumatic switchesare well known.

Position switch 150 signals the range section to shift to the highrange, using jaw clutch assembly 92 to connect output shaft 90 withmainshaft 28, as shift finger 140 moves from the 3-4 shift gate 134 tothe 5-6 shift gate 136. Conversely, position switch 150 signals therange section 14 to shift to low as shift finger 140 moves from the 5-6shift gate 136 to the 3-4 shift gate 134. However, it is to beappreciated that range gear selection could alternatively be made byoperation of a button or a switch by the vehicle operator. Yetalternatively, a “repeat H” pattern, like that shown in U.S. Pat. No.6,339,1403 could be employed. All of these arrangements are well knownin the prior art. It is to be appreciated that the precise shift patternis not limited to the embodiments presented herein. However, oneimportant aspect concerns how shifting of the main section is restrictedto protect the auxiliary section synchronizer.

Further, although the range section 14 is illustrated as a two-speedsection which may utilize spur or helical type gearing, it is understoodthat the embodiments presented herein are also applicable to range typetransmissions utilizing combined splitter/range type auxiliary sections,having three or more selectable range ratios and/or utilizing planetarytype gearing. Also, as indicated above, any one or more of clutchcollars 60, 62 or 64 may be of the synchronized jaw clutch type andtransmission sections 12 and/or 14 may be of the single countershafttype.

As noted above, certain situations may arise where the vehicle user, oroperator, requests a shift to low range in the range section of anauxiliary transmission, but completes a shift of the main transmissionbefore the auxiliary transmission completes its shift to low range. Sucha situation may lead to the range piston exerting a force through thesynchronizer on clutch jaws resulting in an undesired level of energydissipation therebetween.

The embodiments presented herein of selector mechanism 112 are key topreventing or reducing such occurrences. The selector mechanism 112provides a mechanism by which an operator manipulating the shift lever114 may laterally position the shift finger 140 in a desired shift gateand then displace the shift finger 140 in a fore-aft direction to engagethe desired main section gear. Embodiments of selector mechanism 112 areshown in detail in FIGS. 9-13, and discussed in greater detail below.The selector mechanism 112 reduces the risk of engaging a main section12 gear before the range shift has been completed, and particularlybefore a range section 14 shift to gear 88 (low range shift) has beencompleted.

As best seen in FIG. 9, selector mechanism 112 also includes a selectormechanism housing 160. Selector mechanism housing 160 serves to coverthe opening in the shift housing assembly 110, as well as to support therest of the parts of selector mechanism 112. Housing 160 defines anelongated cavity 162 therein extending the length thereof. Housing 160rotatably supports a shift member, or shift shaft, 164 disposed incavity 162. Shaft 164 rotates about an axis A-A. A collar portion 166 isaffixed to shaft for rotation therewith. Collar portion 166 includes theshift finger 140, mentioned previously, and an engaging surface, or camsurface, 168. Position switch 150 is mounted to a forward side ofhousing 160 in selective alignment with collar portion 166 as will belater described in more detail.

Briefly referring to FIGS. 7 and 8, and with continual reference to FIG.9, when shift finger 140 is adjacent the 5-6 shift gate 136 or the 7-8shift gate 138, the shift shaft 164 is in a high range position, whichcorresponds to the high range position indicated in FIG. 8.

Selector mechanism 112 also includes a housing extension 170 disposed ata first end of housing 160. Housing extension 170 defines an extensioncavity 172. Extension cavity 172 is generally aligned with cavity 162.Although the illustrated embodiment shows extension 170 as beingseparate from housing 160, and fastened thereto, it is anticipated thathousing 160 could be formed to include extension 170. The main reasonfor forming extension 170 as a separate piece is to permit the use ofthe embodiments described herein with a stock of existing housings 160not having the features of extension 170. Cavities 162, 172 are closed,at least in part, by an end plate 176 fastened to housing extension 170opposite housing 160.

With reference to FIG. 11, embodiments of selector mechanism 112 may besimilar to FIG. 9 and also include a dual pressure switch 178, similarto position switch 150. Dual pressure switch 178, like position switch150, has a plunger 180. It is to be appreciated that dual pressureswitch 178 may also be characterized as a two position valve, directinghigh pressure fluid to actuator assembly 96 in a first condition, andlow pressure fluid to actuator assembly 96 in a second condition. Alocking cam ring 182 is disposed over and fixed to shaft 164 by aretaining pin 184 such that locking cam ring 182 moves unitarily withshaft 164. Dual pressure switch 178 is in selective alignment withlocking cam ring 182 as will be later described in more detail. Thelocking cam ring 182 includes a shift shaft engaging portion 186 and acam surface 188. When dual pressure switch 178 is aligned with lockingcam ring 182, it engages the cam surface 188. Cam surface 188 axiallydisplaces plunger 180 between a first position and a second positionrelative to axis A-A, thereby cycling dual pressure switch 178 betweenfirst control condition and a second control condition as will bedescribed in more detail below.

FIGS. 12A-12D illustrate the relative positions of shift shaft 164within selector mechanism 112 to demonstrate the relative positions ofthe locking piston engaging portion 198 and the shift shaft engagingportion 186. Specifically, FIG. 12A illustrates selector mechanism 112with shift finger 140 adjacent to, or within, the low-rev gear range ofshift gate 130. FIG. 12B illustrates selector mechanism 112 with shiftfinger 140 adjacent to, or within, the 1-2 shift gate 132. FIG. 12Cillustrates selector mechanism 112 with shift finger 140 adjacent to, orwithin, the 3-4 shift gate 134. Additionally, FIG. 12D illustratesselector mechanism 112 with shift finger 140 adjacent to, or within, the5-6 shift gate 136. As illustrated in FIGS. 12A and 12D, the lockingpiston engaging portion 198 cannot interfere with the shift shaftengaging portion 186 to prevent rotation of shift shaft 164. Asillustrated in FIGS. 12B and 12C, the locking piston engaging portion198 may interfere with the shift shaft engaging portion 186 to preventrotation of shift shaft 164.

As best seen in FIG. 13, an embodiment of selector mechanism 112 mayalso include a main section neutral interlock 190. Main section neutralinterlock 190 includes a locking piston 192 is disposed in a cylinderbore, or interlock chamber, 194 formed in housing extension 170 inalignment with and opposite dual pressure switch 178. The locking piston192 has a coaxial stem 196 extending towards axis A-A. Stem 196 has alocking piston engaging portion 198 complementary in shape to the shiftshaft engaging portion 186 in locking cam ring 182. Stem 196 slideswithin a clearance bore 200 passing from cylinder bore 194 into thehousing cavity 162. Clearance bore 200 is enlarged by a springcounterbore portion 202 at the end proximate to cylinder bore 194. Areturn coil spring 204 encircles stem 196, and is disposed in clearancebore 200. Spring 204 biases the locking piston 192 away from axis A-A,and tends to disengage the locking piston engaging portion 198 of stem196 from shift shaft engaging portion 186.

An O-ring seal 206 is disposed in a groove circumscribing the lockingpiston 192. Seal 206 seals the locking piston 192 relative to cylinderbore 194 while permitting relative movement therebetween. Engagement oflocking piston engaging portion 198 in shift shaft engaging portion 186prevents shifting the main section 12 out of neutral under certainconditions as will be explained in more detail below.

A dowel 208 extends from an inboard side of the locking piston 192parallel to stem 196 and is slidably disposed in an aperture 210parallel to clearance bore 200 in housing extension 170. Dowel 208 andaperture 210 cooperatively maintain the rotative alignment of lockingpiston engaging portion 198 relative to shift shaft engaging portion186. Preferably, shift shaft engaging portion 186 is a slot formed inlocking cam ring 182 parallel to axis A-A.

Preferably, the locking piston engaging portion 198 has a square endthat engages with shift shaft engaging portion 186. Also preferably, aplane generally defined by the locking piston engaging portion 198 isgenerally parallel to a plane defined by the shift shaft engagingportion 186. In this manner, attempts by an operator to shift lever 114while the locking piston engaging portion 198 is engaged with the shiftshaft engaging portion 186 will result in interference between tworelatively flat, parallel surfaces, thereby reducing wear on surfaces ofthe locking piston engaging portion 198 and the shift shaft engagingportion 186.

Cylinder bore 194 is closed, and the locking piston 192 retainedtherein, by a cylinder cover 212 disposed over cylinder bore 194. In oneembodiment, cover 212 has a first cavity 214 disposed over andcommunicating with cylinder bore 194. Cover 212 has a fitting feature216 with a passageway 218 therein intersecting cavity 214, enablingfluid communication from cylinder bore 194 to the exterior of cover 212.Fitting feature 216 is configured to accommodate a pre-selected pipe orhose connector. A plug 220 having a bleed orifice 222 is disposed inpassageway 218. Bleed orifice 222 is, in a preferred embodiment, 0.040inches in diameter. Air flowing in and out of cylinder bore 194 mustpass through orifice 222. Cover 212 is clamped against housing extension170 by a plurality of screws 226.

Caps 228 disposed over a spring biased detent plungers which provide thevehicle operator a sense of having shifted between the high range andthe low range. The bias springs and plungers and an associated ringmounted on shaft 164 are not relevant to the present embodiment, and arenot shown. Also not shown are elements within housing which tend to biasshaft 164 to a predetermined position along axis A-A within housing 160.

Referring back to FIGS. 2, 5, and 7-9, a connecting crank 230 is clampedto an end of shaft 164 opposite the end where the locking cam ring 182is positioned. Connecting crank 230 is connected through shift linkage116 to shift lever 114. A cylindrical accordion-type seal 232, combinedwith a sealing ring 236, seals shaft 164 relative to housing 160.Lateral movement of shift lever 114 by the vehicle operator axiallydisplacement of shaft 164 along axis A-A and corresponding lateralmovement of shift finger 140 between shift gates 130, 132, 134, 136,138. Fore-aft movement of shift lever 114 rotates shaft 164 about axisA-A, resulting in fore-aft movement of shift finger 140. Such fore-aftmovement of shift finger 140 results in displacement of a one of theshift forks 100, 102 and 104 depending on the shift gate 130, 132, 134,136, 138 in which shift finger 140 is disposed prior to the initiationof the fore-aft movement.

It is appreciated that the precise form and location of switches 150 and178 may be varied without effect. For example, an electrical switch incombination with a solenoid could be substituted for switches 150 and178. Further, switches 150 and 178 or substitutes therefore could belocated in other places where there is motion relating to the mainsection gear engagement, such as at shift lever 114 or at the shiftrails 120, 122, 124.

FIG. 14 illustrates the range section shifting actuator assembly 96 inmore detail. In the orientation shown, the actuator assembly 96 is inthe “high” range, with gear 86 locked to output shaft 90 by jaw clutchassembly 92.

Actuator assembly 96 includes a piston 240 and a cylinder housing 244. Aconnecting rod 246 fixes the piston 240 to the range shift fork 94.Piston 240 is clamped against a shoulder of connecting rod 246 by alocking nut 248. Cylinder housing 244 has a through bore 250 whichslidably receives connecting rod 246. Through bore 250 opens to acylindrical piston bore 252 in which piston 240 is slidably disposed. AnO-ring 254 seals piston 240 against piston bore 252. Piston bore 252 isclosed, and piston 240 retained therein, by an actuator cylinder cover256 disposed over piston bore 252. Housing 244 and cover 256, at leastin part, define a piston chamber, or range chamber, 260.

The piston 240 divides the piston chamber 260 into a high range side 262and a low range side 266. Supplying pressure to the high range side 262displaces the range shift fork 94 to engage jaw clutch assembly 92 withgear 86, shifting the range section 14 to the range high ratio.Supplying pressure to the low range side 266 displaces the range shiftfork 94 to engage jaw clutch assembly 92 with gear 88, moving the piston240 to a low range condition and shifting the range section 14 to therange low ratio.

A range sensor valve 270 is disposed in line with the connecting rod246. Range sensor valve 270 has a plunger 272 displaced by theconnecting rod 246, indicating that the range section 14 is fullyengaged in the range low ratio, or low condition. In such a condition,although inconsistent with the orientation of the elements in FIG. 14,piston 240 would be fully displaced to the right side of chamber 260.Thus provided, the range sensor valve 270 detects the position, or theengaged ratio of the range section 14. As illustrated in FIG. 14, thepiston 240 is in the left side of chamber 260, and the range section 14is engaged in the range high ratio.

With continuing reference to FIGS. 9 and 14, position switch 150 is atwo position switch with in which plunger 152 is spring biased to afirst position. In a first position, position switch 150 communicatespressurized air to the low range side 266 of actuator piston chamber 260and simultaneously opens the high range side 262 of actuator pistonchamber 260 to exhaust. In a second position, position switch 150communicates pressurized air to the high range side 262 of actuatorpiston chamber 260 and simultaneously opens the low range side 266 ofactuator piston chamber 260 to exhaust. Engagement of plunger 152against a cam surface 168 integrated into collar portion 166 movesposition switch 150 between the first and second positions. Axialmovement of shaft 164 causing shift finger 140 to move from 3-4 shiftgate 134 to 5-6 shift gate 136 results in plunger 152 being moved to thesecond position. Conversely, axial movement of shaft 164 causing shiftfinger 140 to move from 5-6 shift gate 136 to 3-4 shift gate 134 resultsin plunger 152 being moved to the first position.

As described below, illustrated embodiments of a shift inhibitor utilizeat least some of the components described herein. That is, the shiftinhibitor encompasses those portions of the transmission 10 that reducethe undesirable shifting of the main section 12 into a gear when therange section 14 is not in the desired condition, as described ingreater detail below. In the event that the main section 12 shift iscompleted before a desired range section 14 shift is completed, therange section 14 may be in a “neutral” ratio, wherein neither gear 86 or88 is engaged with the jaw clutch assembly 92. If the range section 14is in the “neutral ratio”, the actuator assembly 96 may not shift therange section 14 into a ratio, and the transmission 10 may be in“neutral”, where input shaft 16 is not engaged with output shaft 90,although the operator has manipulated the shift lever 114 into a desiredgear (FIG. 2).

With specific reference to FIGS. 13 and 15, a first embodiment will bedescribed. In the first embodiment, actuator assembly 96, main sectionneutral interlock 190 and position switch 150 are employed. Dualpressure switch 178, cam surface 188 and range sensor valve 270 are notemployed. As shown in FIG. 15, position switch 150 is connected to ahigh pressure air supply line 300 and to exhaust 302 in the form of aport or a line. Position switch 150 is also connected via a first airline 304 to high range side and via a second air line 306 to low rangeside 266. Position switch 150, as described above, connected air lines304 and 306 to high pressure air via supply line 300 and to exhaust 302.Neutral interlock 190 is connected to first air line 304 by a third airline 308. In the present embodiment, range sensor valve 270 is notemployed.

The exhaust 302 performs as a common air line for exhausting both therange chamber 260 and the interlock chamber 194. That is, when exhaust302 is connected to the first air line 304, both air lines 304 and 308are exhausted. Therefore, exhaustion of the interlock chamber 194, influid communication with the air line 308, and the range chamber 260, influid communication with the first air line 304, is initiated generallyconcurrently as both the range chamber 260 and the interlock chamber 194are, at least in part, exhausted simultaneously.

With continual reference to FIGS. 13 and 15, operation of the firstembodiment will be discussed. When the position switch 150 is in a lowrange position, pressurized air is supplied via air line 306 to actuatorassembly 96, engaging range section 14 in the low range condition.Movement of shift lever 114 by the operator from the 3-4 position to the5-6 position (FIG. 8) causes shift finger 140 to move to the 5-6 gate136, and position switch 150 to be switched by displacement of plunger152 to the high range position. This causes the air in low range side266 to be exhausted simultaneously with pressurized air being suppliedto high range side 262 via the first air line 304. Pressurization of thehigh range side 262 and the first air line 304 also cause the lockingpiston 192 to be biased toward axis A-A against the force of spring 204.As shown in FIG. 12D, locking piston engaging portion 198 is not inalignment with shift shaft engaging portion 186 in the 5-6 position ofshaft 164. Displacement of piston to its fully extended position willnot be immediate with the application of pressure, due to the time delaycaused by orifice 222, as discussed above.

When a downshift is made from the 5-6 gate 136 to the 3-4 gate 134 (i.e.from the 5-6 throw position 146 to the 3-4 throw position 144), positionswitch 150 (FIG. 8) is actuated, and locking piston engaging portion 198slides into shift shaft engaging portion 186 (FIG. 12C). With lockingpiston engaging portion 198 so engaged in shift shaft engaging portion186, the operator is unable to move the shift lever in a fore-aftdirection to engage a main section gear. At the same time, due to theaction of position switch 150, air line 306 is pressurized and air line304 exhausted. However, because of the orifice 222 restriction, cylinderbore 194 is not exhausted immediately. It accordingly delays the timebefore which the vehicle operator can successfully complete a mainsection shift into gear. Given the anticipated line air pressure of 80psi (pounds per square inch) and the orifice diameter of approximately0.040 inches, the expected resultant delay will be approximately 0.8seconds. A delay time of approximately one second is preferred. Once thetime period of approximately one second has lapsed, the vehicle operatorwill be able to shift into the desired gear. The delay of 0.8 secondshas been found to provide adequate time for the shift to low range to becompleted by actuator assembly 96 in most circumstances.

With specific reference to FIGS. 14, 16 and 17, a second embodiment isillustrated. Orifice 222 and dual pressure switch 178 and cam surface188 are not employed. Cover 212 need only provide an attachment meansfor an air line. As shown in FIG. 16, position switch 150 is connectedto a first high pressure air supply line 350 and to exhaust 352 in theform of a port or a line. Position switch 150 is also connected via afirst air line 354 to the high range side 262 and via a second air line356 to low range side 266. Position switch 150, as described above,connected air lines 354 and 356 to high pressure air via supply line 350and to exhaust 352. A second high pressure air supply line 358 isconnected to the range sensor valve 270. The range sensor valve 270 isconnected to neutral interlock 190 by a third air line 360. The rangesensor valve 270 has an exhaust port 362. The range sensor valve 270 isa two position valve. In a first condition indicative of the actuatorassembly 96 not being in a low range condition, high pressure air ispassed from the air supply line 358 to air line 360 to bias the lockingpiston 192 toward axis A-A (FIG. 17). In a second condition indicativeof the actuator assembly 96 being in a low range condition, the rangesensor valve 270 blocks the high pressure air from the air supply line358 to air line 360, and connects the air line 360 to the exhaust port362.

Operation of the second embodiment may be as follows. When the positionswitch 150 is in a low range position, consistent with shift lever 114manipulating shift finger 140 to be aligned, for example, with the 1-2shift gate 132 or the 3-4 shift gate 134 (FIGS. 12B and 12C),pressurized air is supplied via air line 356 to actuator assembly 96,putting the range section 14 in the low range condition. Movement ofshift lever 114 by the operator to the 5-6 position causes shift finger140 to move to the 5-6 shift gate 136, and position switch 150 beingswitched to the high range position (as plunger 152 is displaced by camsurface 168). As best seen in FIG. 16, when position switch 150 isswitched to the high range position, the air in low range side 266 willbe exhausted (via the second air line 356) as pressurized air issupplied to high range side 262 (via the first air line 354). As thehigh range side 262 is pressurized, the connecting rod 246 is urged awayfrom the range sensor valve 270 (FIG. 14) and the range section 14 isshifted to the high range position as jaw clutch assembly engages withmainshaft 28 (FIG. 1). As mentioned earlier, the range sensor valve 270detects the actuator assembly 96 not being in a low range condition, andcauses pressured air to flow from the air supply line 358 to air line360.

Pressurization of air line 360 (due to the movement of shift finger 140from within the3-4 shift gate 134 to within the 5-6 shift gate 136)causes pressurized air to travel from the range sensor valve 270 to theneutral interlock 190. As pressurized air enters the neutral interlock190, the locking piston 192 is biased toward axis A-A against the forceof spring 204. As best illustrated in FIG. 12D, when the shift lever 114is in the 5-6 position, locking piston engaging portion 198 is not inalignment or engagement with shift shaft engaging portion 186.Displacement of the locking piston 192 to its fully extended positionwill be nearly immediate with the direction of pressurized air via airline 360.

When the operator downshifts from the 5-6 gate 136 to the 3-4 gate 134,the locking piston engaging portion 198 slides into the shift shaftengaging portion 186 (as best seen in FIG. 12C), thus placing theneutral interlock 190 in a locked condition. With locking pistonengaging portion 198 engaged in shift shaft engaging portion 186,movement of the shift lever 114 in a fore-aft direction is restricted(since rotation of shift shaft 164 is restricted by the interferencebetween the locking piston engaging portion 198 and the shift shaftengaging portion 186). With movement of shift lever 114 thus restricted,an operator cannot engage a main section 12 gear for low range. That is,the 1-2 gate 132 and the 3-4 gate 134 cannot be manipulated to engage agear while the locking piston engaging portion 198 engages the shiftshaft engaging portion 186.

As the shift lever 114 is moved from the 5-6 gate 156 to the 3-4 gate134, position switch 150 is actuated to the low range position (asplunger 152 is displaced by cam surface 168). When the position switch150 is thus actuated, air line 356 is pressurized and air line 354 isexhausted. Concurrently, because of the pressure in air line 360,rotation of shaft 164 continues to be restricted. When the range sensorvalve 270 detects the connecting rod 246, then the range section 14 isin the low range condition (by the depression of plunger 272). Thedepression of plunger 272 causes the range sensor valve 270 to exhaustthe air line 360 through the exhaust port 362.

When the air line 360 is thus exhausted, the locking piston 192 is urgedby spring 204 away from the axis A-A, thereby disengaging the lockingpiston engaging portion 198 from the shift shaft engaging portion 186,and placing the neutral interlock 190 in a released condition. Aslocking piston engaging portion 198 is disengaged from the shift shaftengaging portion 186, the shift shaft 164 is permitted to rotate. Theoperator can then manipulate the shift lever 114 in the fore or aftdirection (FIG. 2) to cause the shift finger 140 to displace either the1-2 gate 132 or the 3-4 gate 134. When either the 1-2 gate 132 or the3-4 gate 134 is displaced, the main section 12 may be engaged.

With specific reference to FIG. 18, a third embodiment is at leastpartially illustrated. Dual pressure switch 178 is employed (see alsoFIG. 13). The range sensor valve 270 and main section neutral interlock190 are not employed. As shown in FIG. 18, position switch 150 isconnected to a dual pressure air supply line 386 and an exhaust 388.Exhaust 388 may be in the form of a port or a line. Position switch 150is also connected via a first air line 390 to high range side 262 ofactuator piston chamber 260. Position switch 150 is further connectedvia a second air line 392 to low range side 266 of actuator pistonchamber 260. Position switch 150, as described above, operably connectsair lines 390 and 392 to dual pressure air via supply line 386 and toexhaust 388. The dual pressure air line 386 is connected to a dualpressure regulator 394 from which the dual pressure air supply line 386receives pressurized air. A master supply air line 396, providing highpressure air, is connected to a first branch 398 connected to the dualpressure regulator 394. Master supply air line 396 is also connected todual pressure switch 178 by a second branch 402. A control air line 404interconnects dual pressure switch 178 with dual pressure regulator 394.

When control air line 404 is vented via dual pressure switch 178, dualpressure regulator 394 supplies high pressure air to the dual pressureair supply line 386. When control air line 404 is pressurized via dualpressure switch 178, dual pressure regulator 394 supplies low pressureair to the dual pressure air supply line 386.

Dual pressure switch 178, in a first condition illustrated in FIG. 18,blocks high pressure air from reaching dual pressure regulator 394,allowing the transmission of high pressure, approximately 80 pounds persquare inch (psi), to be transmitted to dual pressure air supply line386. In a second condition, not illustrated, dual pressure switch 178communicates high pressure air to dual pressure regulator 394 whichresults in dual pressure regulator 394 reducing the pressure of airtransmitted by dual pressure regulator 394 from first branch 398 to dualpressure air supply line 386 to approximately 20 psi. In an embodiment,the high pressure air is in a range of about 30 psi to about 110 psi,and the air transmitted by dual pressure regulator 394 from first branch398 to dual pressure air supply line 386 is in a range of about 5 psi toabout 30 psi. FIG. 19 illustrates a preferred range of positions 410within the shift pattern 142 where the dual pressure switch 178 maycause a high pressure air to be supplied to the actuation assembly 96.

An exemplary operation of the third embodiment is as follows. When themain section is in neutral, as determined by the engagement betweenplunger 180 and cam surface 188, dual pressure switch 178 signals thedual pressure regulator 394 to allow full pressure to reach positionswitch 150 and to thus reach range actuator assembly 96. When the mainsection is in gear (gates 1-2, 3-4, 5-6 or 7-8), dual pressure switch178 communicates full pressure to dual pressure regulator 394, therebyregulating the pressure supplied to position switch 150 to 20 psi. Thislower pressure is adequate to hold a range synchronizer of jaw clutchassembly 92 in gear in the event that range section 14 shifting wascompleted before the main section 12 shift was completed, but not highenough to damage a range synchronizer of jaw clutch assembly 92 if therange section 14 shift was not completed before the main section 12shift was completed.

While the dual pressure regulator 394 is described as a singlecomponent, preferably contained within a single housing, the dualpressure regulator 394 may be provided as an adjustable regulator thatincreases pressure relative to the shift lever position, and may also bea regulator in parallel with a high pressure line that includes a 3-wayvalve capable of supplying either the high pressure or the regulatedpressure to the piston chamber 260.

It should be appreciated that the first and third embodiments could beused in the same transmission with the third embodiment providing asecondary, or back-up, means of protecting the range synchronizers ofjaw clutch assembly 92. FIG. 13 illustrates the combination of the mainsection neutral interlock 190 of the first embodiment with the dualpressure switch 178 of the third embodiment. While the third embodimentis described as having the dual pressure switch 178 connect a highpressure source to the piston chamber 260 of the range section shiftingactuator assembly 96 when the shift lever 114 is in any neutralposition, the dual pressure switch may be configured to connect thepiston chamber 260 with a high pressure source only when the shift leveris in the range of positions 410 illustrated in FIG. 19, therebyreducing the neutral positions of shift lever 114 that result in anundesired increase in pressure against range piston 240 when a rangesection 14 shift is not desired.

While the working fluid used in the illustrated embodiments is describedas air, the fluid may be any suitable fluid including a liquid that isgenerally incompressible, and thus not pressurized as air, but displacedin reaction to an outside force or pressure. Furthermore, theapplication of the working fluid may be used to displace a piston,rotate an impeller, or to provide any other hydraulic/pneumatic tomechanical energy transfer. Additionally, while the control signalsdescribed herein are transmitted via a fluid such as air, to a device,such as a piston, the control signals may be transmitted via optical,electrical, or mechanical conveyances to suitable devices, although thecontrol signals are preferably transmitted through movement of air.

The preceding description has been presented only to illustrate anddescribe exemplary embodiments of the methods and systems of the presentinvention. It is not intended to be exhaustive or to limit the inventionto any precise form disclosed. It will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted for elements thereof without departing from the scope of theinvention. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from the essential scope. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe claims. The invention may be practiced otherwise than isspecifically explained and illustrated without departing from its spiritor scope. The scope of the invention is limited solely by the followingclaims.

1. A shift inhibitor apparatus for encouraging the completion of a rangeshift in a range section of multispeed transmission prior to thecompletion of a main shift in a main section of the multispeedtransmission, the transmission including an input shaft and an outputshaft, the transmission main section having a plurality of selectivelyengageable ratios, wherein the range section is shiftable between arange high ratio and a range low ratio, the shift inhibitor comprising:a range actuating assembly having a range chamber, wherein at least aportion of said range actuating assembly is moveable between a rangefirst ratio and a range second ratio, said portion of said rangeactuating assembly is moveable, at least in part, in response to a fluidpressure, and said range chamber is selectively in fluid communicationwith a vent; and a main section neutral interlock having an interlockchamber, wherein at least a portion of said main section neutralinterlock is moveable between a first condition and a second condition,said interlock chamber is selectively in fluid communication with saidvent, wherein said range chamber can be exhausted such that said rangesection is selectively switched from said first ratio to said secondratio, and wherein said interlock chamber can be exhausted such thatsaid main section neutral interlock is selectively switched from saidfirst condition to said second condition; and an orifice portioninterposed between the interlock chamber and the vent wherein theorifice portion will delay venting the interlock chamber by at least apreselected amount of time; wherein the shift apparatus provides a timedelay beginning after the initiation of the shift between gears of therange section to encourage completion of the range shift prior tocompletion of the main shift.
 2. The apparatus of claim 1, wherein saidsecond condition is a released condition.
 3. The apparatus of claim 1,wherein said orifice selectively delays the interlock from beingswitched to the second condition until the completion of a range shift.4. The apparatus of claim 1, wherein said range chamber and saidinterlock chamber are selectively vented through a common fluid line. 5.The apparatus of claim 1, wherein said interlock selectively retains themain section of the transmission in a neutral condition.
 6. Theapparatus of claim 1, wherein said interlock selectively permitsrotation of a shift member when in the released condition, therebypermitting a gear shift in the main section of the transmission.
 7. Theinhibitor of claim 1, wherein at least a portion of a shift member isrotatable to selectively engage the input shaft with the output shaft,and at least a portion of said shift member is axially moveable toselectively engage a plurality of shift gates.
 8. The apparatus of claim1, wherein said interlock cannot restrict movement of a shift memberwhen the shift member is in a high range position.
 9. The apparatus ofclaim 1, wherein said interlock selectively restricts rotation of ashift member when in the locked condition.
 10. The apparatus of claim 1,further comprising a shift member, wherein the shift member includes ashift finger that selectively engages at least one of a plurality ofshift gates to selectively engage at least one of the plurality of theselectively engageable ratios.
 11. The apparatus of claim 1, furthercomprising a shift member, wherein the shift member includes an engagingsurface, and wherein said engaging surface selectively engages aposition switch.
 12. The apparatus of claim 11, wherein said positionswitch selectively transmits a control signal to said interlock toposition said interlock in the locked condition.
 13. The apparatus ofclaim 12, wherein said control signal is transmitted via a fluid. 14.The apparatus of claim 1, further comprising a shift member, wherein theshift member is manually controlled by a user of the transmission. 15.The apparatus of claim 1, wherein a user manually manipulates a singletransmission input device to selectively engage each gear.
 16. A methodof encouraging the completion of a range shift in a range section ofmultispeed transmission prior to the completion of a main shift in amain section of the multispeed transmission, wherein the multispeedtransmission includes an input shaft, an output shaft, the range sectionshiftable between a first ratio and a second ratio, and the main sectionhas a plurality of selectable gear ratios, the method comprising thesteps of: shifting the main section from a first predetermined gear to asecond predetermined gear, wherein said step of shifting the mainsection includes the steps of initiating a shift between gears of themain section and completing the shift between gears of the main section;detecting a position of a shift member, wherein said step of detectingis performed after said step of initiating the shift between gears ofthe main section and before said step of completing the shift betweengears of the main section; shifting the range section from the firstratio to the second ratio, wherein said step of shifting the rangesection includes the steps of initiating a shift between gears of therange section and completing the shift between gears of the rangesection, wherein said step of shifting the range section is performed,at least in part, by a fluid actuated device; prohibiting the shiftingof the main to the second predetermined gear by engaging an interlock torestrict movement of a shift member; and selecting an orifice innerdiameter of an orifice portion to provide at least a preselected timedelay between the initiation of the shift between gears of the rangesection and the initiation of the shift between gears of the mainsection.
 17. The method of claim 16, further comprising releasing theshift member, wherein said step of releasing permits the shift member toselectively engage the output shaft with the input shaft.
 18. The methodof claim 17, wherein the step of shifting the range section furthercomprises the step of venting a range chamber, the step of releasingfurther comprises the step of venting the interlock chamber through anorifice, and wherein said steps of venting are performed, at least inpart, currently such that the orifice delays the completion of saidreleasing step until after the completion of said step of shifting therange section.
 19. The method of claim 17, wherein said step ofreleasing is delayed a predetermined amount of time to permit thecompletion of said step of shifting the range section prior to thecompletion of said step of releasing.